No, while the Assembly of State Parties oversees the operation of the Court institutions, I can't find any indication that individual members of the Assembly have the privilege to appear before the Court in particular cases that way.
Representing that a defendant is not guilty is a function for defense counsel; the Assembly of State Parties acts essentially as a legislative body.
The ICC has a multilateral "Office of the Prosecutor" to go along with its multilateral court, and that prosecutor, just like any other prosecutor, can be talked down from an indictment, or convinced to drop charges, before the trial begins. I presume that the member-nation delegates can go to the prosecutor, just like city police can go to a regular municipal prosecutor, and say "Hey, why do you think we'll win this? This is silly. Don't charge the guy. Or drop the charges. They won't stick."
But since all the member-nations have access to the same evidence-base, and are following the same strict definition of what constitutes a "war criminal" (i.e. the Geneva convention), they tend to all arrive at the same preliminary conclusion. If they didn't, that'd actually be cause for alarm. So there isn't that much auditing going on. It's usually pretty freakin' obvious—given the evidence that is introduced along with the nomination—who should or should not be standing before the ICC.
(Presumably, at any time, any delegate from a member-nation can stand before the court and say "What the heck are you guys on? This guy isn't a war criminal at all." I don't think that's ever happened—has it?—but it's not like the organization is yet so venerable and hidebound by tradition that it's unable to veer away from a course once it's on it.)